What happens if an account that is configured on a mail client as IMAP is also configured as POP3

By using the IMAP protocol, the emails are
saved on the server and all the users who access the account, through client or
from the webmail, can view them. Should users, when setting-up the shared
account, set the incoming mail protocol to POP3 (without selecting the
‘Leave a copy of the messages on the Server’ option)they will
download all the incoming messages found on the server and these will no longer
be available to users who access the account using the IMAP protocol, or our webmail.